1. Technical Field
The present invention relates to a method of controlling the position of a water curtain device of an on-water floating type, which is used for the promotion or stoppage of the diffusion of inflammable gas, poisonous gas or high-temperature gas leaking from a ship, reduction in the spread of radiant heat in the case of combustion of such inflammable gas, or the like. The present invention particularly relates to a method of controlling the position of such an on-water water curtain device so as to move the device to an optimal position in consideration of the influence of the direction of wind and the tidal current.
2. Background Art
When low-temperature, liquefied inflammable gas, such as liquefied natural gas (LNG) and liquefied petroleum gas (LPG), which is transported by a ship, leaks onto the water due to an accident such as the collision of ships, the gas diffuses through quick evaporation due to the heat of the water so that an explosion or a fire is likely to occur over a wide area. If the explosion or the fire occurs, high-temperature gas is generated. When poisonous gas, which is transported by a ship, leaks onto the water due to an accident, such as the collision of ships, and diffuses, the gas is likely to contaminate the environment or cause a human disaster. It is conceivable that a device for making a water curtain, as used for a low-temperature liquid storage facility or the like on the ground, to preclude such dangerous gas from diffusing around or exerting an influence of heat, may be floated on the water so as to be used for disaster prevention. However, if the water curtain must surround an entire ship, the device is necessarily long and large. This is undesirable from the viewpoint of the efficiency of the conveyance, disposition and so forth of the device to or at the site of an accident and the viewpoint of economy. For that reason, the water curtain device must be disposed only at the dangerous area where the gas leaks. However, there is a problem that since the position of the ship and the direction of the leak of the gas change due to the tidal current and the direction of the wind, the water curtain device needs to be moved depending on the change.